Camera assemblies of this type are used, in particular, for capturing a vehicular environment, for example, for driver assistance systems. The camera assembly includes a camera that is adhesively bonded, for example, via a camera mount to an inner side of the vehicle window pane, in particular of a windshield of the vehicle, or, for example, also fastened to a rearview mirror or to the ceiling of the vehicle. It is also known to use the camera to perform additional secondary functions, for example, to detect objects on the vehicle window pane, in particular to detect raindrops.
Light in the visible spectral region can be used to sense the vehicular environment, for example, particularly other road users and road signs as well; light in the infrared region, i.e., IR radiation, can also be used in night vision systems.
Published International Patent Application No. WO 2010/76065 describes a camera system, which, as a primary image, produces an image of a vehicular environment, and, as a secondary image, captures an area of an outer surface of the vehicle window pane. To record the secondary image, a first mirror is configured in a lower portion of the area of coverage, and another mirror is provided above the objective lens. Thus, the objective lens uses two deflecting mirrors to sense a coating that adheres to the outer side of the window pane essentially above the objective lens. Accordingly, such a system requires adequate installation space, respectively space for mounting the deflection mirrors.
However, auxiliary optics designs for cameras that include mirrors, for example, as discussed in Published International Patent Application No. WO 2010/76065 are relatively expensive. They require additional optical means, as well as appropriate positioning and alignment of the camera relative to the vehicle window pane.
Published International Patent Application No. WO 2012/098192 discusses mounting a prism on an inner surface of the vehicle window pane, the prism forming an optical coupling body. In this case, the design of the prismatic coupling body is such that the phenomenon of a wavelength-selective beam broadening caused by dispersion by the prism on the imager module does not occur since the beam broadening is below the resolution of the image sensor. Thus, the light propagates from the vehicular environment through the vehicle window pane, through the optical coupling body disposed on the inner surface of the vehicle window pane, to the camera optics, and onto the image sensor.
However, the relative position between the coupling body and the camera is generally not clearly defined when the coupling body is attached in this manner, so that there is the risk of a misadjustment.
Published International Patent Application Nos. WO 03/074333 and WO 03/074964 describe using additional holding means or fixing means for imperviously fastening a camera to the windshield, for example, tubular objects adhesively bonded to the inner surface. Therefore, they stop scattered light and prevent a dirt accumulation or a condensation on the windshield in the relevant area.
Generally, therefore, the outlay for equipment for such imaging systems and for the optical adjustment thereof is relatively substantial. In the case of a rain sensor system, for example, a mirror mounted underneath the area of coverage is usually provided to sense a vehicular environment. It deflects the beam path toward the sky. This has a negative effect on the optical imaging properties and the rain sensor system over the course of a day, particularly if there is considerable brightness due to solar irradiation, for example. Furthermore, the optical imaging path of such systems is relatively short, so that partial degradation of the optical properties can occur.
These types of camera systems also require an unobstructed view through the vehicle window pane, for example, near the ceiling. When a camera assembly of this kind is mounted in an upper portion of the vehicle window pane, in particular of the windshield, it is also necessary in conformance therewith to reserve space for an optionally provided black tinting or other type of darkening. To some extent, the free space required for this is considerable, especially because of the slant of the vehicle window pane. Thus, there can be a shortage of space if additional functions are located in this area.